GA-DM induces caspase-dependent apoptosis in melanoma cells. (A) Western blot analysis shows protein expression and cleavage of caspases 9 and 3 in melanoma cells treated with vehicle alone (control) versus 40μM of GA-DM for 24 h. β-actin was utilized as a loading control. (B, C) Inhibition of caspases by a pan caspase inhibitor, Z-VAD-FMK, decreased GA-DM-induced cell death in J3 and HT-144 melanoma cells. Cells were treated with vehicle alone or GA-DM (40μM) for 3, 6, 12, and 24 h in the presence or absence of Z-VAD-FMK at 37°C, followed by the MTS viability assay as described. Experiments were repeated at least three times, and data were expressed as mean ± S.D. Significant differences were calculated by student's t test; *p <0.001.